Process for production of detergent tablets



United States Patent 3,455,834 PROCESS FOR PRODUCTION OF DETERGENT TABLETS Milton N. Kraus, Hillsdale, NJ., assignor to Colgate- Palmolive Company, New York, N.Y., a corporation of Delaware No Drawing. Filed Jan. 22, 1964, Ser. No. 339,326

Int. Cl. Clld 3/06, 3/16 U.S. Cl. 252135 3 Claims ABSTRACT OF THE DISCLOSURE Improved detergent tablets containing sodium tripolyphosphate are prepared by treating the compressed tablets with super-heated steam at a temperature above 450 F. for less than seconds and then cooling to ambient temperatures for at least one-half minute, the moisture content of the tablet remaining unchanged.

This invention relates to a new and improved process for preparing detergent tablets. More particularly it relates to a process for making detergent tablets in commercial production which will have sufficient strength to permit packaging and handling without breakage yet be capable of being easily removed from the package and of rapid disintegration under ordinary washing machine use.

The prior art has shown various detergent tablets and methods for producing such tablets. The use of detergent tablets particularly in the laundering of textiles or soiled clothes permits the consumer to utilize a premeasured quantity of detergent material thereby eliminating the need for measuring devices such as are used with detergent granules and liquids. Tablets also eliminate the usual problems of spillage and over and under-usage encountered with the use of detergent granules or liquid.

The prior art has disclosed a number of means of producing detergent tablets but such means have not been completely satisfactory from a commercial standpoint. In general, the tablets of the prior art have not had the necessary physical strength to completely withstand the shipping and handling which occurs prior to use by the consumer. Where the physical strength has been adequate the tablets would often not readily disintegrate in the requisite period of time. Furthermore, tablets having the necessary physical strength quite often adhered to each other in the package as a result of processing, thereby making it extremely diflicult for the consumer to separate the tablets prior to use.

It is an object of this invention to provide a high speed process for making detergent tablets which have the physical strength to withstand high speed packaging and shipping. It is a further object to provide a process which reduces or eliminates tablet cohesion in the consumer package.

It has now been discovered that the objects of the present invention may be obtained by compressing a detergent composition into tablets, treating the compressed tablets with superheated steam at a temperature above about 450 F. for less than about 10 seconds, and then cooling the steam treated tablets for at least about onehalf minute to reduce the tablet temperature to about ambient temperature to provide cooled tablets having sub- Patented July 15, 1969 stantially the same moisture content as before steam treatment.

It has been found in carrying out the present invention that any detergent composition suitable for use in preparing tablets, such as the tablet compositions described in U.S. Patent 2,875,155 to Miles or US. 3,081,267 to Laskey are suitable for use in the present invention. The detergent composition is formed into tablets by compressing the desired amount of detergent powder in a tablet press at pressures of between 3-350 p.s.i.

In general, the tablet compositions which are suitable for use in the present invention will contain a water-soluble polyphosphate such as the alkali metal polyphosphates and a water-soluble, non-soap organic detergent selected from the group consisting of anionic and nonionic detergents. Such tablets may also contain the usual adjuvant materials such as perfumes, foam stabilizers, foaming agents, whiteners, preservatives, etc.

The anionic detergents are the anionic non-soap synthetic detergents which may be designated as water-soluble salts of organic sulfuric reaction products having in their molecular structure an alkyl or acyl radical of carbon atom content within the range of about 8-18 and a sulfonic acid or a sulfuric acid ester radical. Typical of these anionic detergents are: sodium or potassium alkyl benzene sulfonate in which the alkyl group contains from about 9 to about 15 carbon atoms in either a straight chain or branched chain which is derived from polymers of propylene; sodium and potassium alkyl glyceryl ether sulfonates, especially those ethers of higher fatty alcohols derived from the reduction of coconut oil; the reaction product of higher fatty acid with sodium or potassium isethionate, where, for example, the fatty acids are derived from coconut oil; sodium or potassium alkyl sulfonates and sulfates, especially those alkyl sulfates derived by the sulfonation of coconut or tallow fatty alcohols and mixtures of such alkyl sulfates; di-alkyl esters of sodium or potassium salts of sulfosuccinic acid, for example, the dihexyl ester; sodium and potassium salts of sulfated or sulfonated monoglycerides derived, for example, from coconut oil; sodium or potassium salts of the higher fatty alcohol esters of sulfocarboxylic acids, for example, the sodium salt of the lauryl alcohol ester of sulfoacetic acid; sodium or potassium salts of a higher fatty acid amide of methyl taurine in which the higher acyl radical for example, are derived from coconut oil: and the like.

Non-ionic, non-soap synthetic detergents may be broadly classed as being constituted of a water-solubilizing polyoxyethylene group in chemical combination with an organic hydrophobic compound such as polyoxypropylene, alkyl phenol, the reaction product of an excess of propylene oxide and ethylene diamine, and aliphatic alcohols. The non-ionic synthetic detergents have a molecular weight in the range of from about 800 to about 11,000. Typical of the non-ionic detergents are those made available under the trade name of Igepal and Sterox. These compounds are formed by condensing ethylene oxide with an alkyl phenol. The addition of polyoxyethylene radicals to this hydrophobic base increases the Watersolubility of the entire molecule. Liquid products are obtained up to a point, higher proportions of polyoxyethylene rendering the product solid in consistency. Examples of such non-ionic synthetic detergents useful in the present invention are: condensation products of 10-30 moles of ethylene oxide with one mole of an alkyl phenol containing 6-12 carbon atoms, either in a straight or branched chain in the alkyl group (e.g. nonyl or dodecyl phenol); condensation products of 10-30 moles of ethylene oxide with one mole of an aliphatic straight or branched chain alcohol containing 8-18 carbon atoms (e.g. lauryl alcohol or tallow fatty alcohol), condensation products of ethylene oxide and the reaction product of propylene oxide and ethylene diamine where the reaction product has a molecular weight of 2,5003,000, for example, and the condensation product has a polyoxyethylene content of 40%80% In addition other nonionic non-soap synthetic detergents known in the art such as those known under the trade name Pluronics may be employed.

The detergent composition may be formed into tablets by any conventional tablet forming method. The tablets of this invention may be made of any of various shapes and sizes depending upon the purpose for which they are to be used. The tablet surfaces may be scored, if desired, to facilitate division by the consumer.

The prepared tablets after being removed from the tablet forming equipment are treated with superheated steam at a temperature above about 450 F. for less than about 10 seconds. Preferably, the tablets should be treated with the superheated steam at a temperature of about 600-1000 F. for about 1-5 seconds and most preferably about 3 seconds. It is essential in carrying out the present invention that the steam employed be superheated and at sufiicient positive pressure to permit flow. While substantially atmospheric pressure is preferred, pressures in the order of or pounds may be employed satisfactorily. Higher steam pressures may be employed but do not appear to provide any advantages over lower pressures.

It has been found that the use of superheated steam for extremely short periods of time greatly strengthens the surfaces of the detergent tablets and at the same time avoids undesirable tackiness which was common in prior art processes. The prior art in general teaches the need to increase the moisture content of the tablet by either water addition or non-superheated steam treatment. In the present invention, it is of the utmost importance that the tablet moisture content immediately after steaming is substantially the same as that prior to the steam treatment. Furthermore, it is of the utmost imporance that condensation on the interior of the steaming equipment be avoided so that the moisture content of the tablet surfaces passing through the equipment is not increased as a result of condensation moisture wetting the table surfaces.

The tablets may be treated with superheated steam in batch or continuous operations. Preferably, the tablets will be treated on a continuous belt. Both sides of the tablets may be treated simultaneously with the superheated steam but it is preferred to treat one side at a time. Where it is desired to treat both sides of the tablet simultaneously, an open type continuous belt may be employed.

After steam treatment, and preferably before being packaged, the tablets are cooled to ambient temperature in a period of about one-half to one minute in order to obtain maximum surface strength and minimum tackiness. While cooling may be carried out for longer periods of time, no additional advantage is obtained. In fact, in commercial production, it is desirable that the tablets be cooled in the minimum time, to avoid processing time losses. If the tablets are not cooled prior to packaging, tackiness presents a problem. By the term tackiness is meant that physical condition which exists when the tablets have a somewhat sticky surface due to the presence of undesirable moisture which permits the packaged tablets to stick to each other making subsequent separation diflicult.

The following examples are given to further illustrate the means by which this invention can be carried out.

Example I Detergent tablets prepared from a spray dried powder containing Optical brighteners, coloring, perfume, sodium carboxymethylcellulose and other adjuvant materials 3.0

were, immediately after being formed into tablets, transferred to a 3 inch wide wire mesh conveyer belt which travelled through a steam chamber approximately 20 inches long. Superheated steam at a temperature of 750 F. was introduced into the chamber through a steam header located at the top of the chamber. The tablets passing through the steam chamber were located approximately Ms inch below the surface of the steam diffuser nozzles employed. The tablets passed through the steam chamber in approximately 3 seconds, were turned over and passed through a second steam chamber in approximately 3 seconds in order to treat the other side. Each side of the tablets exiting from the second steam chamber was subjected to cooling air having a temperature of about 70 F. and a fiow rate of 50-60 c.f.m. per square foot for one minute. The cooled tablets were then packaged by conventional detergent tablet packaging means.

The superheated steam treated tablets had the same moisture content as before treatment, the desired physical strength and showed no signs of breaking when subjected to the stresses and handling typical of packaging and transporting operations. The tablets disintegrated in water at 100 F. in 20-60 seconds.

Example II Detergent tablets containing Percent Sodium sulfate 10.0 Sodium tripolyphosphate 50.0 Pentadecylbenzene sulfonate 18.0 Sodium silicate (Na OzSio ratio of 1:2) 6.0 Water 14.0

Optical brighteners, coloring, perfume, sodium carboxymethylcellulose and other adjuvant materials 2.0

Example III Detergent tablets containing Percent Sodium sulfate 11.5 Sodium tripolyphosphate 53.0 Dodecylbenzene sulfonate 12.0 Lauryl myristic isopropanylamide 1.5 Pentadecylbenzene sulfonate 18.0 Sodium silicate (Na ozsiO ratio of 1:2) 6.0 Water 14.0

Optical brighteners, coloring, perfume, sodium carboxymethylcellulose and other adjuvant materials 2.0

were treated by the procedure of Example I using superheated steam at a temperature of 750 F. for approximately 3 seconds.

The superheated steam treated tablets had the same moisture content as before treatment, the desired physical strength and showed no signs of breaking when subjected to the stresses and handling typical of packaging and transporting operations. The tablets disintegrated in water at 100 F. in 20-60 seconds.

Example IV Detergent tablets containing Percent Sodium sulfate 27.0 Sodium tripolyphosphate 40.0 Alkyl dimethylbenzyl ammonium chloride 1.0

Dodecyl benzene sulfonate 12.0

Soap (tallow) 3.0 Sodium silicate (Na O:SiO ratio of 1:2) 5.0 Water 10.0 Optical brighteners, coloring, perfume, sodium carboxymethylcellulose and other adjuvant materials 2.0

What is claimed is:

1. A process for preparing detergent tablets which comprises compressing into tablets at a pressure of about 3-350 p.s.i. a detergent composition mixture consisting essentially of sodium tripolyphosphate and a Water-soluble, non-soap organic detergent selected from the group consisting of anionic and non-ionic detergents said tripolyphosphate constituting a major portion of the mixture of said tripolyphosphate and detergent, treating said compressed tablets with superheated steam at a temperature above 450 F. for less than 10 seconds and cooling to room temperature said steamtreated tablets prior to packaging in order to avoid tacking, said cooled tablets having substantially the same moisture content as before steam treatment.

2. The process according to claim 1 wherein the tablets are treated with superheated steam at a temperature of 6001000 F. for 1-5 seconds.

3. The process according to claim 1 wherein the tablets are treated with superheated steam at a temperature of 750 F. for 3 seconds.

References Cited UNITED STATES PATENTS 2,875,155 2/1959 Miles 252-138 3,081,267 3/1963 Laskey 252 3,231,506 1/ 1966 Schulerud 252138 3,247,123 4/ 1966 Schrager et al. 252-435 LEON D. ROSDOL, Primary Examiner B. BETTIS, Assistant Examiner US. Cl. X.R. 252--1 38, 161 

